In vitro effects of a mixture of Escherichia coli heat-stable enterotoxins on chloride flux in everted jejunal sacs of male pigs.

In vitro effects of a mixture of Escherichia coli heat-stable enterotoxins (STa and STb) on isolated jejunum of 3-week-old male pigs were studied, using everted intestinal sac techniques. Heat-stable enterotoxins increased chloride secretion and chloride absorption in everted intestinal sacs. The increase of secretory flux was greater than that for absorptive flux. Vasoactive intestinal peptide (6 x 10(-9) M) increased chloride secretion, but had no effect on chloride absorption. Neither vasoactive intestinal peptide nor pilocarpine (10(-5) M) had additive effect to ST. Secretory effects of ST were not blocked by atropine (2 x 10(-5) M), clonidine (10(-6) M), or morphine (4.2 x 10(-6) M).